The present invention is generally in the area of using polymeric hydrogel-cell compositions in medical treatments.
Craniofacial contour deformities
Craniofacial contour deformities, whether traumatic, congenital, or aesthetic, currently require invasive surgical techniques for correction. Furthermore, deformities requiring augmentation often necessitate the use of alloplastic prostheses which suffer from problems of infection and extrusion. A minimally invasive method of delivering additional autogenous cartilage or bone to the craniofacial skeleton would minimize surgical trauma and eliminate the need for alloplastic prostheses. If one could transplant via injection and cause to engraft large numbers of isolated cells, one could augment the craniofacial osteo-cartilaginous skeleton with autogenous tissue, but without extensive surgery.
Unfortunately, attempts to inject dissociated cells subcutaneously or to implant dissociated tissues within areas of the body such as the peritoneum have not been successful. Cells are relatively quickly removed, presumably by phagocytosis and cell death.
Cells can be implanted onto a polymeric matrix and implanted to form a cartilaginous structure, as described in U.S. Pat. No. 5,041,138 to Vacanti, et al., but this requires surgical implantation of the matrix and shaping of the matrix prior to implantation to form a desired anatomical structure.
Vesicoureteral reflux.
Vesicoureteral reflux is a condition wherein there is an abnormal development of the ureteral bud as it enters the bladder during embryologic development. The shortened course of the ureter through the bladder musculature decreases the ureteral resistance and allows for urine to reflux from the bladder reservoir back up into the ureter and into the kidney. With this condition, bacteria which may occasionally be present in the bladder through retrograde urethral transport, can reach the kidneys and cause recurrent pyelonephritis. In addition, the constant back pressure of the urine into the calyces and renal pyramids results in mechanical damage to the renal parenchyma. If untreated, urinary vesicoureteral reflux can cause loss of renal parenchyma, and in some instances, renal failure, as reviewed by Atala and Casale, Infections in Urology 39-43 (March/April 1990). In 1960, 70% of the patients with renal failure were described as having vesicoureteral reflux as the primary etiology. With the advent of new diagnostic and treatment modalities, patients with vesicoureteral reflux now account for less than 1% of the renal failure population.
In the past, vesicoureteral reflux was usually diagnosed with a voiding cystogram after the child presented with repeated episodes of pyelonephritis. With the increased use of prenatal and postnatal sonography, hydronephrosis is more detectable, prompting further radiologic workup and earlier detection, as reported by Atala and Casale. Vesicoureteral reflux is graded depending on the severity. Grade 1 reflux signifies that urine is seen refluxing from the bladder up to the ureter only; in grade 2 reflux, urine refluxes into the ureter and calyceal dilatation. Grade 4 and 5 reflux are more severe, showing ureteral tortuosity and further calyceal blunting and dilatation, respectively.
The treatment of vesicioureteral reflux has been well established over the last decade. Initially it was believed that all patients with reflux would require surgery. Another school of management soon proposed that only medical therapy with antibiotics was required. It is now well established that the treatment of reflux depends on many factors, including the severity of reflux, associated congenital abnormalities, and the social situation of the child (parental compliance with medical treatment). Medical treatment is usually recommended for patients with grade 1 and 2 reflux, which usually resolve on their own as the bladder/ureteral configuration changes with growth. Grade 3 reflux is generally managed with medical therapy unless it persists or breakthrough infections occur while on antibiotic suppression. Surgical treatment is usually required for grade 4 and 5 reflux.
Medical treatment implies that the patient is treated with daily suppressive antibiotics. A close follow-up is required in these patients, generally consisting of a catheterized urine culture every three months, an ultrasound exam and serum analysis every six months, a fluoroscopic or nuclear voiding cystourethrogram every year, and a DMSA renal scan every two years. Surgical treatment consists of an open surgery wherein a low abdominal incision is made, the bladder is entered, the ureters are mobilized and new ureteral submucosal tunnels are created; thereby extending the muscular backing of the ureter which increases their resistance. These patients require a general endotracheal anesthetic for a four to five hour surgery, an epidural catheter for both intraoperative and postoperative pain control, a bladder catheter for drainage, a perivesical drain, and a five to six day hospital stay. Antibiotic therapy and bladder antispasmodics are required post-operatively.
Although open surgical procedures for the correction of reflux have excellent results in the hands of experienced surgeons, it is associated with a well recognized morbidity, including pain and immobilization of a lower abdominal incision, bladder spasms, hematuria, and post-operative voiding frequency in some children. In an effort to avoid open surgical intervention, widespread interest was initiated by Matouschek's clinical experience with the endoscopic injection of Teflon.TM.(polytetrafluoroethylene) paste subureterally in 1984, as reported in Matouschek, E.: Die Behandlung des vesikorenalen Refluxes durch transueterale Einspritzung von polytetrafluoroethylenepast. Urologe, 20:263 (1981). With this technique, a cystoscope is inserted into the bladders, a needle is inserted through the cystoscope and placed under direct vision underneath the refluxing ureter in the submucosal space, and Teflon.TM. paste is injected until the gaping ureteric orifice configuration changes into a half-moon slit. The Teflon.TM. paste, injected endoscopically, corrects the reflux by acting as a bulking material which increases ureteral resistance. However, soon after the introduction of this treatment, a controversy regarding the use of Teflon.TM. paste ensued. Malizia et al. "Migration and granulomatous reaction after periurethral injection of polymer (polytetrafluoroethylene)" JAMA, 251:3277 (1984), showed granuloma formation and particulate migration to the brain, lungs, and lymph nodes in animal studies. Polytetrafluoroethylene migration and granuloma formation have also been reported in humans by Claes et al., "Pulmonary migration following periurethral polyetrafluoroethylene injection for urinary incontinence" J. Urol., 142:821 (1989). The safety of Teflon.TM. for human use was questioned, and the paste was thereafter banned by the FDA.
However, there are definite advantages in treating vesicoureteral reflux endoscopically. The method is simple and can be completed in less than fifteen minutes, it has a success rate of greater than 85% with low morbidity and it can be performed in an outpatient basis, as reported by Atala et al, "Endoscopic treatment of vesicoureteral reflux with a self-detachable balloon system" J. Urol. 148:724 (1992). The goal of several investigators has been to find alternate implant materials which would be safe for human use.
Bovine dermal collagen preparations have been used to treat reflux endoscopically. However, only 58.5% of the patients were cured at one year follow-up, as described by Leonard et al, "Endoscopic injection of glutaraldehyde cross-linked bovine dermal collagen for correction of vesicoureteral reflux" J. Urol. 145:115 (1991). The collagen implant volume decreases with time, which results in high percentage of recurrence of reflux, over 90% within 3 years. The high failure rate with this substance presents a high risk to the unaware patient of developing renal damage after treatment.
A paste consisting of textured microparticles of silicone, suspended in a hydrogel, has been injected subureterally to correct reflux with an initial success rate of 91% in one European study, as reported by Buckley at al., "Endoscopic correction of vesicoureteric reflux with injectable silicone microparticles" J. Urol. 149: 259A (1993). However, distant particle migration has been observed in animal models, as reported by Henly et al., "Particulate silicone for use in periurethral injections: a study of local tissue effects and a search for migration" J. Urol. 147:376A (1992). Approximately thirty percent of the silicone particles have a diameter which is less than 100 .mu.m. This suggests that thirty percent of the silicone particles have a potential for distant organ migration through the macrophage system. The manufacturer of this technology tried unsuccessfully to obtain FDA approval, and subsequently filed for bankruptcy.
Laparoscopic correction of reflux has been attempted in both an animal model (Atala et al, "Laparoscopic correction of vesicoureteral reflux" J. Urol. 150:748 (1993)) and humans (Atala, "Laparoscopic treatment of vesicoureteral reflux" Dial Ped Urol 14:212 (1993)) and is technically feasible. However, at least two surgeons with laparoscopic expertise are needed, the length of the procedure is much longer than with open surgery, the surgery is converted from an extraperitoneal to an intraperitoneal approach, and the cost is higher due to both increased operative time and the expense of the disposable laparoscopic equipment.
Despite the fact that over a decade has transpired since the Teflon.TM. controversy, little progress has been made in this area of research. The ideal substance for the endoscopic treatment of reflux should be injectable, non-antigenic, non-migratory, volume stable, and safe for human use (Atala et al, 1992).
Urinary incontinence.
Urinary Incontinence is the most common and the most intractable of all GU maladies. Urinary incontinence, or the inability to retain urine and not void urine involuntarily, is dependent on the interaction of two sets of muscles. One is the detrusor muscle, a complex of longitudinal fibers forming the external muscular coating of the bladder. The detrusor is activated by parasympathetic nerves. The second muscle is the smooth/striated muscle of the bladder sphincter. The act of voiding requires the sphincter muscle be voluntarily relaxed at the same time that the detrusor muscle of the bladder contracts. As a person ages, his ability to voluntarily control the sphincter muscle is lost in the same way that general muscle tone deteriorates with age. This can also occur when a radical event such as paraplegia "disconnects" the parasympathetic nervous system causing a loss of sphincter control. In different patients, urinary incontinence exhibits different levels of severity and is classified accordingly.
The most common incontinence, particular in the elderly, is urge incontinence. This type of incontinence is characterized by an extremely brief warning following by immediate urination. This type of incontinence is caused by a hyperactive detrusor and is usually treated with "toilet training" or medication. Reflex incontinence, on the other hand, exhibits no warning and is usually the result of an impairment of the parasympathetic nerve system such as a spinal cord injury.
Stress incontinence is most common in elderly women but can be found in women of any age. It is also commonly seen in pregnant women. This type of incontinence accounts for over half of the total number of cases. It is also found in men but at a lower incidence. Stress incontinence is characterized by urine leaking under conditions of stress such as sneezing, laughing or physical effort. There are five recognized categories of severity of stress incontinence, designated as types as 0, 1, 2a, 2b, and 3. Type 3 is the most severe and requires a diagnosis of intrinsic Sphincter Deficiency or ISD (Contemporary Urology, March 1993). There are many popular treatments including weight loss, exercise, medication and in more extreme cases, surgical intervention. The two most common surgical procedures involve either elevating the bladder neck to counteract leakage or constructing a lining from the patient's own body tissue or a prosthetic material such as PTFE to put pressure on the urethra. Another option is to use prosthetic devices such as artificial sphincters to external devices such as intravaginal balloons or penile clamps. For treatment of type 3 stress incontinence, there has been a recent trend toward injection of Teflon.TM. or collagen paste around the sphincter muscle in order to "beef up" the area and improve muscle tone. None of the above methods of treatment, however, are very effective for periods in excess of a year.
Overflow incontinence is caused by anatomical obstructions in the bladder or underactive detrustors. It is characterized by a distended bladder which leads to frequent urine leakage. This type of incontinence is treated acutely by catheterization and long-term by drug therapy. Enuresis or bedwetting is a problem in pediatrics and is controlled by various alarming devices and pads with sensors. Enuresis is not considered a serious problem unless it lasts beyond the age of four or five. Finally, there is true functional incontinence which occurs in patients with chronic impairment either of mobility or mental function. Such patients are usually treated by the use of diapers, incontinence pads or continuous catheterization (BBI, 1985 Report 7062).
WO 94/25080 describes the use of injectable polysaccharide-cell compositions for delivering isolated cells by injection. There is a need for improved injectable polymer-cell compositions which are biocompatible and biodegradable for delivering isolated cells by injection or implantation.
Accordingly, it is an object of the present invention to provide methods and compositions for injection of cells to form cellular tissues and cartilaginous structures.
It is a further object of the invention to provide improved compositions to form cellular tissues and cartilaginous structures including non-cellular material which will degrade and be removed to leave tissue or cartilage that is histologically and chemically the same as naturally produced tissue or cartilage.
It is another object of the present invention to provide improved methods and materials for treating vesicoureteral reflux, incontinence, and other defects which results in a natural and permanent cure to the defect.
It is a further object of the present invention to provide methods and materials for treating vesicoureteral reflux, incontinence, and other defects which is quick, simple, safe, and relatively non-invasive.